Fibrillation. The Latest Management Strategies

Transcription

1 Atrial Fibrillation The Latest Management Strategies

2 CONTENTS ABOUT JOHNS HOPKINS MEDICINE...1 ABOUT THE AUTHORS...3 ATRIAL FIBRILLATION: THE MOST COMMON ARRHYTHMIA...4 SYMPTOMS, CAUSES, AND RISKS OF ATRIAL FIBRILLATION DIAGNOSING ATRIAL FIBRILLATION ANTICOAGULATION THERAPY FOR ATRIAL FIBRILLATION SUPPRESSING AF SYMPTOMS: RATE CONTROL SUPPRESSING AF SYMPTOMS: RHYTHM CONTROL CATHETER ABLATION OF ATRIAL FIBRILLATION SURGICAL ABLATION OF ATRIAL FIBRILLATION DECIDING ON APPROPRIATE TREATMENT ARRHYTHMIA GLOSSARY... 61

3 ABOUT JOHNS HOPKINS MEDICINE M uch of what we take for granted in medicine today from the rigorous training of physicians and nurses to the emphasis on research and the rapid application of that research to patient care emerged from innovations made more than a century ago at a brand new medical center in Baltimore: Johns Hopkins. Hopkins now uses one overarching name Johns Hopkins Medicine to identify its whole medical enterprise. This $6.7 billion virtual organization unites the physicians and scientists of The Johns Hopkins University School of Medicine with the health professionals and facilities that make up the broad Johns Hopkins Health System. A little history: Toward the end of the 19th century, American medical education was in chaos; most medical schools were little more than trade schools. Often, it was easier to gain admission to one of these than to a liberal arts college. With the opening of The Johns Hopkins Hospital in 1889, followed four years later by The Johns Hopkins University School of Medicine, Johns Hopkins ushered in a new era marked by rigid entrance requirements for medical students, a vastly upgraded medical school curriculum with emphasis on the scientific method, the incorporation of bedside teaching and laboratory research as part of the instruction, and integration of the School of Medicine with the Hospital through joint appointments.

4 Hopkins medicine counts many firsts among its achievements during its early years: the first major medical school in the United States to admit women; the first to use rubber gloves during surgery; the first to develop renal dialysis and CPR. Two of the most far-reaching advances in medicine during the past 25 years were made at Hopkins. The Nobel Prize-winning discovery of restriction enzymes gave birth to the genetic engineering industry and can be compared, some say, to the first splitting of an atom. Also, the discovery of the brain s natural opiates has triggered an explosion of interest in neurotransmitter pathways and functions. Other accomplishments include the identification of the three types of polio virus and the first blue baby operation, which opened the way to modern heart surgery. Hopkins also was the birthplace of many medical specialties, including neurosurgery, urology, endocrinology and pediatrics. 2

5 ABOUT THE AUTHORS HUGH G. CALKINS, M.D. Dr. Calkins is the Nicholas J. Fortuin, M.D., Professor of Cardiology, Professor of Pediatrics, and Director of the Arrhythmia Service, the Electrophysiology Lab, and the Atrial Fibrillation Center at The Johns Hopkins Hospital. He has clinical and research interests in the treatment of cardiac arrhythmias with catheter ablation, the role of device therapy for treating ventricular arrhythmias, the evaluation and management of syncope, and the study of arrhythmogenic right ventricular dysplasia. Dr. Calkins has authored more than 500 manuscripts and chapters. He was lead author of the 2007 and 2012 HRS/EHRA/ECAS Consensus Document on Catheter and Surgical Ablation of Atrial Fibrillation and is also a member of the writing group for the 2013 ACC/AHA/HRS Atrial Fibrillation Guidelines. Dr. Calkins is a member of the editorial boards of five major cardiology journals.. RONALD BERGER, M.D., PH.D. A Professor of Medicine and Biomedical Engineering at Johns Hopkins, Dr. Berger is Director of the Electrophysiology Fellowship Program at The Johns Hopkins Hospital. He serves on the editorial boards of three major journals in the cardiovascular field, has authored more than 200 articles and book chapters, and holds over 20 patents on methods and devices used in electrophysiology diagnosis and treatment. Along with Dr. Hugh Calkins, Dr. Berger and his colleagues perform approximately 3,500 electrophysiology procedures and 500 atrial fibrillation ablation procedures each year.

6 ATRIAL FIBRILLATION: THE MOST COMMON ARRHYTHMIA Aracing heartbeat is familiar to anyone who has had to run up a flight of stairs or has been in a frightening situation. But for the estimated 2.6 million Americans who suffer from atrial fibrillation (AF or AFib), that sensation of a fast, irregular, and chaotic heartbeat all too often becomes a way of life. Moreover, for many, it severely impairs their quality of life and may put their health at risk. Recent studies have reported a link between AF and dementia. AF is remarkably common. It is found in approximately 1% of the general population, and it s the most common cardiac arrhythmia seen by doctors today. Men and women over age 40 have a 1 in 4 lifetime risk of developing AF. The ailment becomes more likely with age. AF is rare prior to the age of 50 years, but by the age of 80, 10% of individuals will have AF. It s estimated that 70% of all AF patients are between the ages of 65 and 85. By the year 2050, some 12 million Americans are expected to have AF due to an aging population as well as the obesity epidemic, with more than half of people affected by AF expected to be over the age of 80. How AF Affects the Heart The heart beats close to 100,000 times a day. That s about 70 beats per minute, every minute, every hour, every day, every year. However, for some people, the rhythmic lub-dub, lub-dub, lub-dub of the heart is not as precise as a Rolex. For some reason, the heart s electrical system goes haywire, leading to less efficient blood circulation and an irregular and chaotic pulse. That s because the heart s atria (upper chambers) quiver rather than contract forcefully, which then leads to an irregular and often rapid beating of the lower heart chambers, called the ventricles. The sinoatrial (SA) node (also referred to as the sinus node), which is located in the upper right atrium, acts as a natural pacemaker that governs the heart s rate and rhythm. Special muscle fibers in the heart then conduct these electrical messages through the chambers. When a normally functioning SA node controls heart rhythm, it s called normal sinus rhythm. 4

7 However, the specialized cells of the SA node are not the only ones capable of controlling electrical stimulation; the millions of heart muscle cells all have the ability to create their own electrical signals, disrupting the normal sinus rhythm in the process. If these cells misfire, the heart may race from a normal resting rate of 60 to 90 beats per minute (bpm) up to 200 bpm, then slow down after a few moments. This irregularity may occur hundreds of times a day, or only in several short episodes a year. These misfirings can result in what are called premature or ectopic beats that is, coming from a source other than the SA node. If there is a so-called run of premature beats in the atria, the heart rhythm can go into what s called atrial fibrillation. This fibrillation the multiple or rapid firing of electrical signals from different areas of the atria rather than the SA node alters the movement of blood through the atria. In cases where a person s heartbeat is extremely fast as high as 190 beats per minute after getting out of bed or rising from a chair symptoms such as shortness of breath, dizziness, weakness, palpitation, or chest pain may occur, and can range from mild to severe. Some people complain that it feels as if my heart is going to jump out of my chest. AF, by far the most common sustained arrhythmia, can last for minutes, hours, days, or weeks. While it s not always possible or even necessary to restore the heart to normal rhythm, most physicians attempt to restore the normal tempo of a healthy heart for those who have symptoms and an impaired quality of life as a result of the heart rhythm abnormality. AF and Stroke Contrary to popular belief, AF itself is not usually life threatening. However, the presence of AF increases the risk of blood clots (embolisms) forming in the heart, and if a clot travels to the brain, a stroke will result. The stroke risk in patients with AF is up to seven times that of the general public and the incidence of stroke attributable to AF increases with age, dramatically so after age 80. Upwards of 24% of all ischemic strokes (strokes caused by a blood clot blocking a narrowed artery or a clot that travels to the brain from somewhere else in the body) are due to AF. Moreover, strokes related to AF are often major strokes that have worse outcomes than non-af strokes, with a greater likelihood of significant disability or death. Making Treatment Decisions A nuisance to some, a danger for others, AF runs the gamut of patient complaints and has many possible solutions if, in fact, a solution is needed. In this special report, we will first review the symptoms and causes of AF and then discuss what is involved in diagnos- 5

8 THE HEART S ELECTRICAL SYSTEM Each heartbeat is initiated by an electrical signal. The signal originates in a group of cells in the right atrium called the sinoatrial (SA) node and travels throughout the atria toward a region in the center of the heart called the atrioventricular (AV) node. This causes the atria to contract, pushing blood into the ventricles. The signal then travels through a network of specialized fibers to all parts of the ventricles. The ventricles contract, and blood is sent into the aorta and other arteries in the body. Arrhythmias are abnormalities in the heart s rhythm. They can occur if the SA node develops an abnormal rate or rhythm, if the electrical signal is interrupted along its route, or if another part of the heart beats faster than the SA node and produces its own electrical signal. The end result is an irregular and sometimes fast heart rate. While a normal heart rate is between 60 and 100 beats per minute, heart rate in AF can jump between 100 and 180 beats per minute many times during a one-minute interval. In arrhythmias called supraventricular tachycardias, the atria contract too rapidly. AF is a type of supraventricular tachycardia in which the atria quiver and do not contract effectively. In ventricular tachycardia, the ventricles contract too rapidly, while in ventricular fibrillation, the ventricles quiver, and do not contract effectively. The term bradycardia is used to indicate that the heart is beating too slowly. Normal Heart Rhythm An electrical signal originates in the SA node, travels through the atria and the AV node, and continues into the ventricles. (Arrows denote pathway of electrical signal.) Atrial Fibrillation The electrical activity in the atria becomes chaotic and uncoordinated, so that the atria quiver rather than contract effectively. Ventricular Fibrillation Chaotic and uncoordinated electrical activity in the ventricles causes the ventricles to quiver rather than contract effectively. Heart Block A cause of bradycardia in which the AV node delays or prevents the electrical signal from traveling from the atria to the ventricles. ing and treating AF. We address what we first ask about any patient: Do we need to do anything to reduce the risk of stroke? Many people are at low risk, and so we don t need to do anything. But for those who score high on a basic self-test evaluating their risk, anticoagulation therapy is strongly recommended. Anticoagulation therapy in these patients has been shown not only to dramatically reduce stroke risk, but it also lowers mortality by approximately 30%. AF treatment strategies, including rate and rhythm control (with medication or catheter or surgical ablation), are also discussed in detail. 6

9 sinoatrial (SA) node left atrium right atrium atrioventricular (AV) node right ventricle left ventricle Normal Heart Rhythm An electrical signal originates in the SA node, travels through the atria and the AV node, and continues into the ventricles. (Arrows denote pathway of electrical signal.) Atrial Fibrillation The electrical activity of the atria becomes chaotic and uncoordinated, so that the atria quiver and the blood is pumped less effectively into the ventricles. Ventricular Fibrillation Chaotic and uncoordinated electrical activity in the ventricles causes them to quiver rather than pump blood to the rest of the body. A point we make with our patients is that, unlike some arrhythmias, AF is generally not a life-threatening problem. For most people, it s just a darned nuisance. The reason to do something about AF, if something is done at all, is because of the bothersome symptoms that may adversely affect your quality of life. We have three treatment goals when it comes to AF: Restoration and maintenance of sinus rhythm whenever possible Controlling heart rate 7

10 Preventing clot formation (stroke prevention) As you will read, the various approaches we can take to treat AF or prevent a recurrence of the ailment make use of some of the following: Medications Drug therapy is typically the first line of treatment for AF. Drugs can be used as a monotherapy or in combination as a way to control heart rate during AF, as a way to restore heart rhythm, or simply to reduce AF symptoms. A variety of antiarrhythmic drugs can be used to get the heart back to normal sinus rhythm. The rapid ventricular rate can be controlled with various medications, including betablockers, calcium channel blockers, and digoxin. Anticoagulants that include warfarin (Coumadin) and newer drugs such as dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eliquis) are used for the prevention of ischemic stroke for patients who are at risk. Cardioversion Electrical cardioversion uses a powerful but brief electric shock delivered to the heart through paddles placed on the chest. This helps to restore normal heart rhythm when medication does not improve symptoms. Antiarrhythmia medications are also used to restore and maintain the heart s normal rhythm. Radiofrequency catheter ablation Areas of the heart muscle that trigger abnormal rhythm are eliminated through an innovative minimally-invasive medical procedure called pulmonary vein antrum isolation (PVAI), which delivers concentrated radiofrequency energy waves that heat and destroy a ring of tissue surrounding each pulmonary vein. By achieving electrical isolation of the pulmonary vein, AF is prevented. Cryoballoon catheter ablation Areas of the heart muscle that trigger abnormal rhythm are eliminated by positioning a balloon in each pulmonary vein antrum. Cryothermal energy (freezing) is then applied to the tissue through the balloon to electrically isolate the pulmonary vein, preventing AF. 8

11 Surgical ablation Appropriate candidates for surgical ablation of AF are patients undergoing other cardiac surgical procedures who have bothersome AF symptoms and asymptomatic patients who are undergoing cardiac surgery (and their ablation can be performed with minimal risk). The procedure can also be considered for AF patients who have failed one or more catheter ablation attempts, and also for patients who are not candidates for catheter ablation or prefer a surgical approach. New Therapies, New Guidelines Any patient who experiences an episode of AF needs to be evaluated by a cardiologist, who can determine the best course of therapy. Making treatment decisions can be tricky. Recently, there have been several important revisions to clinical practice guidelines for managing AF. In 2010, the European Society of Cardiology (ESC) revised their entire set of guidelines and issued an additional update in The American College of Cardiology/ American Heart Association (ACC/AHA) published a substantial update to their guidelines in 2011 that incorporates new medications and research data. In addition, the Heart Rhythm Society (HRS) released an expert consensus statement in 2012 (with one of us, Hugh Calkins, as lead author) that describes the science and best practices for catheter ablation. The ACC, AHA, and HRS are currently preparing a complete rewrite of the 2006 and 2011 AF Guidelines. This report makes use of these latest guidelines. It will familiarize you with AF and provide you with detailed information on all key topics, including the newest treatments and it will provide you with the essential questions you ll want to discuss with your doctor. 9

12 SYMPTOMS, CAUSES, AND RISKS OF ATRIAL FIBRILLATION Symptoms of atrial fibrillation (AF) can vary from person to person. Some people with AF are fatigued by the ailment and it puts a crimp on everyday activities; others find themselves short of breath after a little physical exertion. Some people may also find that they have an inability to concentrate. We have a patient who swears his IQ drops 20 points when he goes into AF, leaving him somewhat disabled until the AF passes. Not everyone who develops AF will experience symptoms, and for those who do, symptoms can range from mild to severe. Symptoms of AF can include the following: Fatigue Palpitations (irregular, rapid, or a pounding sensation in the neck or chest) Shortness of breath Lightheadedness Dizziness Chest pain/discomfort Syncope (transient loss of consciousness, or fainting) Causes of Atrial Fibrillation A long list of circumstances and conditions is associated with AF. Multiple factors can contribute to the development of AF and the abnormal functioning of the heart s upper chambers; these include high blood pressure, coronary heart disease, cardiomyopathy (progressive degeneration of the heart muscle), obesity, sleep apnea, and valvular disorders. AF is also associated with diabetes, an overactive thyroid (hyperthyroidism), and pneumonia, and it commonly develops after cardiac surgery. Age is a key factor AF is rare before age 50, whereas 1 in 10 people age 80 have it. AF is also more common in men than in women, and it is more common in whites than blacks. It is also well established that AF can run in families. The presence of a first-degree relative with AF results in a doubling of the likelihood that other members of the family will 10

13 WHAT HAPPENS WHEN YOU HAVE AF Here s a good way to visualize what goes on when you have AF: You re out in the middle of a placid lake in a canoe. You drop a stone overboard, causing the water to ripple out in gentle circles away from the boat. That stone represents your atrioventricular (AV) node and it controls the rhythmic water ripples, which are the heartbeats. When the water is calm again, toss a handful of smaller stones into the water. A chaotic pattern of uncoordinated water ripples develops. This represents your heartbeat in atrial fibrillation. develop AF. Although some specific genetic abnormalities have been reported in some families with AF, this is very unusual and there is currently no clinical role for genetic testing in patients with AF. Alcohol and AF Although some alcohol consumption may help protect against heart disease, your heart may pay a price if you drink excessively. According to a recent study in the journal Circulation, heavy alcohol intake increases the risk of AF in men. Researchers studied 16,415 men and women in Denmark, assessing their intake of beer, wine, and spirits with a questionnaire and performing ECGs to check for the presence of AF. No association was found between moderate alcohol use and AF. But when alcohol intake reached a level of 35 or more drinks per week, men had a 45 to 63% increased risk of AF, compared to men who consumed less than one drink per week. An estimated 5% of the cases of AF in the men were attributed to heavy alcohol consumption. There was no association between alcohol consumption and AF in women, who rarely consumed the high levels of alcohol seen in some of the men. The authors hypothesize that heavy alcohol intake may lead to AF by affecting the structure and size of the heart or by promoting irregular heart rhythms in people predisposed to AF. And some patients develop AF after consuming even small amounts of alcohol. Of course, alcohol consumption, especially heavy consumption, carries other health risks in addition to AF which is why experts recommend that, if you drink alcohol, you should have no more than 1 to 2 drinks a day. In our experience, AF in some patients is uniquely sensitive to alcohol and even one drink my trigger AF. However, this is rare, and for most patients moderate levels of alcohol do not trigger or impact their AF. It is for this reason that we do not routinely tell all patients with AF to stop drinking alcohol. 11

14 Obesity, Sleep Apnea, and AF AF is more common in obese patients. Part of the reason for this is that obese patients are more likely to develop obstructive sleep apnea, or OSA. And AF is very common in patients with OSA, which causes a person s breathing to be interrupted during sleep and is considered one of the most dangerous sleep disturbances. Obesity may also trigger AF by increasing inflammation in the body. An increasing body of research has demonstrated that weight loss can play an important role in improving AF control in many patients. Sleep apnea is quite common, affecting an estimated 12 to 18 million Americans. About 4% of middle-aged men and 2% of middle-aged women have the condition, according to the National Heart, Lung, and Blood Institute. Sleep apnea is caused by a blockage of the airway due to a collapse of the soft tissue at the back of the throat during sleep. People with sleep apnea snore and repeatedly experience brief interruptions of breathing (apnea) during sleep. This may occur hundreds of times during sleep, which deprives the brain and other vital organs of life-sustaining oxygen. These pauses in breathing can cause drastic changes in oxygen levels, putting an enormous strain on the heart that can lead to an increase in heart rate and risk for vascular disease. One fact that has become evident is that there is now a clear link between sleep apnea and cardiovascular problems. It s possible that the constant fluctuation in blood oxygen levels caused by sleep apnea may contribute to arterial inflammation, blood flow obstruction, insulin resistance, and, eventually, increased hypertension and cardiovascular-related events such as AF. A study in The Lancet reported that the risk of a cardiovascular event was three times higher in men with severe apnea. A study in The New England Journal of Medicine noted that sudden cardiac death in people with sleep apnea peaks between midnight and 6 A.M., unlike the general population, where the risk of death sinks to its lowest point during sleeping hours. Sleep apnea is a grossly underdiagnosed disorder. However, it is easily detected with an at-home testing device or in a sleep laboratory, and there are effective treatments for it. When left untreated, sleep apnea can have life-threatening cardiovascular consequences by causing abnormal heart rhythms, high blood pressure, and increased risk of heart attack and stroke. Sleep experts consider sleep apnea to be as great a risk factor for cardiovascular disease as cholesterol, smoking, hypertension, and diabetes. It is for these reasons that it is important to screen AF patients for sleep apnea especially if they are obese or if they snore or their spouse reports they intermittently stop breathing while sleeping. Once diagnosed, treatment of sleep apnea helps control AF. 12

15 Weighty Implications Your risk of developing AF may rise in tandem with your weight. A recent article in the American Heart Journal analyzed 16 studies from two groups of people: 78,600 European adults and about 45,000 heart surgery patients. In the first group, overweight adults were 39% more likely, and obese adults 87% more likely, to develop AF than their normal-weight counterparts. But obesity didn t increase AF risk among those in the second group the patients who d had heart surgery. Although AF is a fairly common complication after certain heart procedures, such as bypass surgery, postsurgical AF may arise for reasons that differ from those in the general population. In people who have not had heart surgery, excess pounds may contribute to AF by causing an enlargement of the left ventricle, the heart s main pumping chamber. This, in turn, may cause the atria to enlarge. In addition, health problems linked to obesity like high blood pressure and diabetes can contribute to AF. The bottom line: AF may be another addition to the list of reasons to control your weight with a heart-healthy diet and regular exercise. The most important step someone can take to reduce the risk of developing AF is to avoid becoming obese. More and more data has confirmed the link between obesity and AF, and there is also data showing that weight reduction can lower the risk of AF. It s also important to avoid hypertension or, if you have it, to treat it aggressively. And anyone who is at risk should avoid drinking high levels of alcohol. Most patients can tolerate small amounts of alcohol and caffeine without triggering an episode of AF. Atrial Fibrillation and the Risks to Health In addition to impacting quality of life, AF increases the risk of heart failure, stroke, dementia, and death. The mortality rate associated with AF is double that of patients with normal sinus rhythm. Moreover, in patients who already have heart failure, AF aggravates the condition. Conversely, heart failure also promotes AF. AF and stroke. As we ve already mentioned, there is a risk of stroke with AF. One in every five ischemic strokes (caused by a blood clot blocking a narrowed artery or a clot that travels to the brain from somewhere else in the body) occurs in patients with AF. That s because blood can pool in the fibrillating atria typically the left atrium making it more likely to clot. Clots can form after just two days, then eventually break off and move to the brain, where they can cause a stroke. In people over age 70, AF is the single most common risk factor associated with stroke. (Text continues on page 18.) 13

16 A CLOSER LOOK AT STROKES Each year approximately 795,000 Americans suffer strokes; just over 600,000 of these are first attacks. On average, someone in the United States has a stroke every 40 seconds. Although the incidence is highest among people over age 65, a stroke may afflict anyone at any age. Most people survive a stroke. But about 20% of stroke victims die shortly after the stroke, and about 25% will have a second stroke within five years. A major consequence of stroke is disability: nearly half of stroke victims experience moderate to severe impairments requiring special care. After heart disease and cancer, stroke is the third leading cause of death and the leading cause of disability among Americans. Thankfully, the death rate from strokes has dropped by more than 34% between 1998 and This decline is probably the result of more aggressive treatment of stroke risk factors (such as hypertension and smoking), earlier diagnosis of strokes, and better treatments. Still, the best weapon against strokes is prevention. Stroke prevention is essential in controlling the devastating physical, emotional, and financial repercussions of cerebrovascular disease. More than half of strokes could be avoided if people took the appropriate preventive steps by embracing and adhering to healthful habits. We should do all we can to prevent strokes, but Americans are much more worried about heart attacks than they are about strokes. A recent survey reported that only 1% of those interviewed mentioned stroke as a leading health concern. By comparison, 13% listed heart disease and 33% mentioned cancer. Surprisingly, even among people who had experienced a stroke or who knew someone who had, only 2% said that strokes were a major health worry. What Is a Stroke? A stroke occurs when an artery that supplies blood to part of the brain becomes blocked or ruptures. As a result, blood flow to a portion of the brain is interrupted, and neurons (nerve cells) in the affected area are deprived of the oxygen and nutrients they need to function properly. These neurons can suffer damage in as little as four minutes; if the deprivation continues for a few hours, neurons cannot survive, and some brain function is lost. The damage to brain cells caused by a stroke can produce lasting disabilities that may impair a person s senses, motor skills, behavior, language ability, memory, and thought processes. The specific deficits that occur depend on which portions of the brain are damaged, as well as the type and severity of the stroke. In addition to these deficits, a stroke may produce long-term problems from erratic sleep patterns and emotional instability to poor judgment and depression. Nerve cell damage due to a stroke is usually permanent, producing such impairments as difficulty walking, speaking, and thinking. Despite the death of neurons, however, people who have had a stroke 14

17 usually have some improvement in function over time, because other neurons gradually take over the functions of those that were lost. There are two basic types of strokes: ischemic and hemorrhagic. Prompt and accurate diagnosis of the stroke type is essential for determining the best treatment; when a stroke has occurred, every minute counts. Ischemic strokes. About 87% of all strokes are ischemic; these result from a blockage in a blood vessel providing blood to the brain. Deprived of oxygen and nutrients, neurons become damaged within minutes and start to die. Further damage is caused by the so-called ischemic (or glutamic) cascade, which leads to a buildup of toxins. Where the blockage occurs and how long it lasts determine whether the brain suffers only temporary impairment, irreversible damage to only a few highly vulnerable neurons, or extensive neurological damage. There are two major types of ischemic strokes: thrombotic and embolic. Thrombotic stroke. The most common type of ischemic stroke is a thrombotic stroke. It occurs when a thrombus (blood clot) forms along the wall of one of the major arteries supplying the brain and completely blocks blood flow. The affected artery may be one of the carotid or vertebral arteries or a smaller artery within the brain itself. Blood clots are most likely to develop in arteries that are already narrowed by fatty deposits called plaques, which also cause coronary heart disease. The hard, rough, uneven surfaces of the plaques are ideal sites for the formation and growth of blood clots. Embolic stroke. This type of ischemic stroke most often occurs when an embolus (part of a blood clot or a piece of atherosclerotic plaque) breaks off and travels through the bloodstream until it lodges in a smaller artery supplying the brain, thus blocking blood flow. Most of these emboli originate in the heart or in large arteries such as the carotid. As discussed on page 5, one of the most common causes of emboli is atrial fibrillation (AF). Because of the abnormal heart rhythm that characterizes AF in which the atria (the upper chambers of the heart) quiver chaotically instead of contracting in a rhythmic pattern the atria do not empty completely of blood. The blood that remains behind can form clots that can escape and ultimately lodge in an artery (usually in the brain). One third of people with untreated atrial fibrillation suffer a stroke. Other conditions that can increase the risk of an embolic stroke include a heart attack, heart failure (an impaired ability of the heart to pump blood), valvular heart disease (damage to one or more of the heart s valves), and plaque in the aorta (the body s main artery). Hemorrhagic Strokes. Hemorrhagic (or bleeding) strokes account for about 13% 15

18 A CLOSER LOOK AT STROKES (CONTINUED) Ischemic strokes Hemorrhagic strokes clot causing embolic stroke burst aneurysm causing subarachnoid hemorrhage plaque causing thrombotic stroke torn artery causing intracerebral hemorrhage of all strokes. These strokes occur when an artery in the brain tears or ruptures and blood leaks into the surrounding tissue. The bleeding can enter tissue deep within the brain itself (an intracerebral hemorrhage) or it can flow into the space between the brain and the skull (a subarachnoid hemorrhage). Damage from a hemorrhagic stroke occurs in two ways: First, the blood supply is cut off to the parts of the brain beyond the site of the tear or rupture. Second and posing greater danger the escaped blood forms a mass that exerts excessive pressure on the brain. Blood continues to leak from the torn or ruptured artery until the blood clots or the pressure inside the skull is equal to the pressure in the damaged artery. An intracerebral hemorrhage is often caused by a tear in a small blood vessel in the brain; a subarachnoid hemorrhage is usually the result of a ruptured aneurysm in the brain. An aneurysm is a blood-filled pouch that balloons out from a weak spot in a blood vessel wall. While some aneurysms are congenital (present at birth), they may be made worse or even caused by hypertension. An intracerebral hemorrhagic stroke also can be caused by the 16

19 rupture of a congenital blood vessel defect known as an arteriovenous malformation (AVM, a tangled web of arteries and veins). The Warning Signals of a Stroke Sudden weakness or numbness of the face, arm, or leg on one side of the body. Sudden dimness or loss of vision, particularly in only one eye. Loss of speech, or trouble talking or understanding speech. Sudden severe, unexplained headaches. Unexplained dizziness, unsteadiness, or sudden falls, especially along with any of the previous symptoms. If you notice one or more of these signs, don t wait. See a doctor right away! About 10% of strokes are preceded by mini-strokes, or transient ischemic attacks (TIAs). TIAs can occur days, weeks, or even months before a major stroke. A person who s had one or more TIAs is 9.5 times more likely to have a stroke than someone of the same age and sex who hasn t. Thus, TIAs which occur when a blood clot temporarily clogs an artery are extremely important warning signs. TIA symptoms occur rapidly and last a relatively short time. More than 75% of TIAs last less than five minutes. The average is about a minute, although some last several hours. By definition, TIAs can last up to but not over 24 hours, although this is very unusual. Unlike a stroke, a TIA leaves no lasting disability. TIA symptoms are very similar to those of stroke; their short duration and lack of permanent damage is the main distinction between TIA and stroke. Although TIAs signal only about 10% of strokes, they re very strong predictors of stroke risk. Don t ignore them! Get medical attention immediately. A doctor should determine if a TIA or stroke has occurred, or if it s another medical problem with similar symptoms (seizure, fainting, migraine, or general medical or cardiac condition). Prompt medical or surgical attention to these symptoms could prevent a fatal or disabling stroke from occurring. Preventing a Stroke It s estimated that more than half of all strokes could be averted if more people took the appropriate preventive steps. Most of the steps for reducing stroke risk are identical to those for preventing a heart attack. These include controlling high blood pressure (the single most important risk factor for stroke); not smoking; losing weight if your body weight is excessive; drinking alcohol moderately (if you drink at all); keeping your cholesterol levels in check; getting regular exercise; and controlling diabetes. Low daily doses of aspirin or other antiplatelet drugs may be prescribed if you have had a TIA or are otherwise at high risk of stroke. If you have AF, your doctor will determine if you should be treated with anticoagulant therapy. (See pages for more information.) 17

20 AF and dementia. Evidence of a link between AF and dementia comes from the Intermountain Heart Collaborative Study, which used data on 37,000 people, average age 60, who were treated in a large hospital system in Utah, Idaho, and Wyoming. Researchers evaluated the subjects for signs of AF and Alzheimer s disease or vascular, senile, or nonspecific dementia. During an average of five years follow-up, 4% of the subjects developed dementia and 27% developed AF. AF was associated with each of the four types of dementia, independent of other cardiovascular disease. The youngest group with AF (under age 70) had the highest incremental risk of dementia: those with AF were 130% more likely to develop Alzheimer s disease. Dementia is linked to older age, so this finding suggests the relationship between AF and dementia is particularly strong. Classification of Atrial Fibrillation Based on a patient s most frequent complaints, AF is classified as paroxysmal, persistent, or longstanding persistent. Here is how we define the three types: Paroxysmal AF is a recurrent condition where the rapid heart rate and abnormal electrical signals spontaneously begin, typically last for a day or two, sometimes as long as a week, and then suddenly disappear as mysteriously as it began. Symptoms can range from barely noticeable to severe. Persistent AF lasts longer than a week, or lasts less than a week but symptoms are stopped following cardioversion (medical or electrical). Longstanding persistent AF is continuous AF that lasts longer than a year and a rhythm control strategy is pursued. At first, patients may have brief episodes of AF, then revert to normal sinus rhythm for extended periods and this pattern may persist for some time. But ultimately, episodes of both paroxysmal and persistent AF may become more frequent and bothersome and eventually may result in longstanding persistent AF. One additional term that is sometimes used is permanent AF and it s less a description of a patient s AF than it is of a therapeutic strategy whereby the patient and physician together have decided not to pursue rhythm control. If a patient is asymptomatic, he can decide to take anticoagulant medication and stay in AF permanently. If subsequently the patient undergoes cardioversion, that would take away the permanent AF status and is followed by efforts to get the patient back to normal sinus rhythm. The patient s status is redesignated as longstanding persistent AF. 18

21 DIAGNOSING ATRIAL FIBRILLATION Symptoms of atrial fibrillation (AF) vary from person to person. Many people with AF have no symptoms and in such people, AF may be detected as an incidental finding during a physical examination or test that has been ordered for some other reason. Palpitations are a common symptom of AF, and if you experience palpitations or any of the other symptoms associated with AF (see page 10) you should make an appointment with your family doctor. If AF is present on your electrocardiogram or if your history suggests atrial fibrillation, your doctor may then refer you to an electrophysiologist for further testing and/or treatment. Electrophysiologists are cardiologists who specialize in the heart s electrical system. These arrhythmia specialists (cardiac electrophysiologists) utilize a patient s medical history plus the results of various procedures to diagnose heart rhythm abnormalities. When an electrical disorder is diagnosed, the electrophysiologist works with your doctor to determine the risk it poses and makes recommendations about possible treatment options. Along with your primary care doctor (or general cardiologist), you and the arrhythmia specialist decide on the best course of action for you. Your doctor will probably ask many of the following questions, so in order to prepare for your visit, write down your answers beforehand. What particular symptoms are bothering you? When did you first begin to experience these symptoms? Did you start taking any new vitamins, supplements, or prescription drugs before the onset of symptoms? Are these symptoms paroxysmal (occasional or intermittent, beginning and stopping on their own), or persistent (present all the time, or lasting at least a week at a time continuously)? On a scale of 1 to 5, with 1 being little or no bother and 5 being severely bothersome, how would you rate your symptoms? Is there anything that appears to worsen your symptoms? Is there anything that appears to lessen your symptoms? Whenever an abnormal heart rhythm is suspected, your doctor may recommend one or more tests to diagnose the arrhythmia and determine if it is causing your symptoms. These tests may include one or more of the following (text continues on page 22): 19

22 GETTING A SECOND OPINION The last time you bought a car or other big-ticket item, you probably spent days or weeks doing research and shopping around before making a final decision. So why would you do anything less when making important decisions about the health of your heart? One way to ensure that your health decisions are informed ones is to seek a second medical opinion. For example, let s say your cardiologist recommends a major procedure perhaps a pulmonary vein antrum isolation for your atrial fibrillation. You might feel more comfortable about undergoing the procedure if another doctor confirms that the treatment is necessary. As medicine grows more complex and the number of treatment options continues to multiply, getting a second opinion is becoming more commonplace and helpful. Yes, your own cardiologist will probably continue to manage your care. But because some doctors are more cautious or conservative in their treatment recommendations, and others are more aggressive, patients may want a different perspective on the same set of medical facts. You might be concerned that your own doctor will be offended if you seek another opinion. That s rarely the case. Today s physicians are quite accustomed to and comfortable with their patients consulting with another doctor to get a second point of view. In fact, with certain types of medical conditions or procedures, most physicians expect their patients to seek another assessment of their disease and the best way to treat it. When To Seek Another Opinion In general, second opinions aren t necessary for everyday medical decisions. If your doctor adjusts the dosage of your antiarrhythmic medication or puts you on a new blood pressure drug, for example, there s usually no need to open the Yellow Pages to look for another doctor s opinion. But when the issue is a procedure for atrial fibrillation or another major decision about your heart, that s the time to consider whether or not you should consult another physician. Here are some situations when you might want to consider a second opinion: You ve been diagnosed with a heart condition by your family doctor or internist, and you want the opinion of a specialist like a cardiologist or electrophysiologist. Your doctor recommends cardiac ablation or another procedure that poses considerable risk or is costly, and you want to make sure the procedure is really necessary. You might also want to seek a second opinion for relatively minor procedures (like the insertion of an implantable pacemaker) if it would make you feel more comfortable before going ahead with the procedure. You have several treatment options to choose from, and you want to make sure that your doctor is recommending the one that most other doctors would recommend as well. Even though cardiologists have gone through similar training, they can have different points of view on managing various heart conditions, including atrial fibrillation. You feel pressured to agree to a particular treatment and are unsure the treatment is the right one for you. 20

23 You live in a small community or rural area where your doctor does not manage many patients with your particular heart condition, and you d like to hear the advice of a doctor affiliated with a major medical center or medical school. Interestingly, your insurance company may insist that you get a second opinion, particularly if your doctor has recommended a major (and perhaps expensive) procedure. In other cases, if you belong to an HMO (health maintenance organization), you might be interested in getting the perspective of a doctor outside of the health organization. You ll probably have to pay for the second opinion out of pocket, but many people believe that it s worth the price for the peace of mind that you have received the best advice on your treatment options. Finding a Doctor Once you ve reached the decision to seek a second opinion, let your physician know and ask him or her for advice on how to proceed. Your primary care doctor should be able to refer you to a cardiologist. And your cardiologist should have the name of another cardiologist in your community who can provide an opinion from a different vantage point. You can also ask family members and friends for the name of a physician who has treated them for the same or similar health problem. If you prefer, call your local medical society, or a nearby medical center or medical school, and request the names of appropriate specialists. If you want to check the credentials of a particular doctor, reference books in the library (such as The Official American Board of Medical Specialists [ABMS] Directory of Board Certified Medical Specialists) can provide the name of the medical school the doctor attended, and where he or she received residency and specialty training. You can also scan the book America s Top Doctors, which compiles lists of leading physicians based on surveys that ask doctors who they themselves would go to for treatment in their own specialty. Before you meet with this new doctor, have your physician send your relevant medical records, including the results of any tests already conducted. You might have to sign a release form for these records to be sent to the new doctor. When Doctors Disagree Sometimes the doctor you choose for a second opinion makes a recommendation different from your own physician. What should you do? In a case like this, don t hesitate to get a third opinion. In fact, many insurance companies will pay for a third opinion when the first two doctors you ve consulted have opposing viewpoints. Here s another option to consider. After getting a second opinion, let both your own doctor and the one you ve consulted know that they ve disagreed about your diagnosis or the best course of action. Suggest that the two physicians confer with one another to discuss your case and to try to reach a consensus. Once each of them has described how and why he or she reached their conclusion, they may find common ground on which they can both agree and make a joint recommendation on what you should do. 21

24 Electrocardiogram (ECG). An electrocardiogram (ECG) is a simple test that traces the electrical activity of your heart. During an ECG, you lie flat on a table, connected to an ECG machine with wires taped to your chest, arms, and legs. The test is painless and takes only a few minutes. The ECG produces a printout that doctors can examine to diagnose arrhythmias or other types of heart disease. When you have AF, the atria produce a signature set of wiggles in the tracing, and the ventricular rate is typically irregular. Holter Monitoring. Holter monitoring is a continuous ECG recording usually for 24 to 48 hours while you go about your normal daily activities. It is useful to detect arrhythmias that may not occur during a resting ECG. During Holter monitoring, wires are connected to your chest and attached to a small recording device that you carry with you. If you experience any symptoms, you are asked to push a button and record your symptoms so that your heart rhythm at the time of your symptoms can be determined. An arrhythmia specialist will later analyze the electrical recordings to determine what your actual heart rhythm was at the time that you were experiencing your symptoms and also whether any asymptomatic abnormal heart rhythms occurred while you were wearing the Holter monitor. Event Monitor. An event monitor is similar to a Holter monitor but it does not record the heart rhythm continuously. Event monitors only record the heart rhythm when an abnormally fast or slow heartbeat occurs or when you activate them. An event monitor is used for one or two months, during which you are instructed to trigger the device and record your symptoms if symptoms occur. Once a recording is obtained, the ECG tracing can be transmitted over the phone to a monitoring station that will analyze the ECG recording and send it to your arrhythmia specialist for interpretation. Implantable Monitor. The implantable monitor is a small device that is inserted under the skin (similar to a pacemaker) and functions like an event monitor. This device is typically recommended for patients who have passing-out spells every three to 12 months and in whom other tests have not determined a cause. One of the advantages of these devices is that they note the amount of time a patient is in atrial fibrillation. The technique involved with inserting this monitor is similar to a pacemaker insertion. However, the incision is smaller, no wires need to be placed in the heart, and the procedure is usually performed on an outpatient basis. Exercise Stress Test. Some arrhythmias only occur while a patient is exercising. Because of this, your doctor may recommend an exercise stress test. During this test, you briskly walk or jog on a treadmill while hooked up to an ECG machine. This allows your arrhythmia specialist to determine if you are experiencing any arrhythmias while exercising and also determine if you have evidence of a blocked heart artery. 22

25 Echocardiogram and Transesophageal Echocardiogram. An echocardiogram is a noninvasive, painless test that allows cardiologists to see if your heart is functioning normally or if it is enlarged or weakened or has a damaged valve. Ultrasound waves are directed through the chest to the heart. The echoes of the sound waves are processed and used to produce images of the heart. Additionally, a transesophageal echocardiogram (TEE) may be performed by having you swallow the ultrasound probe (following numbing medication to the throat and appropriate sedation). The TEE provides close-up images of the heart from the esophagus. This technique is an excellent way to search for blood clots in the atria. Your physician may request that you have a TEE prior to an electrical cardioversion or catheter ablation. Most patients tolerate this test quite well. CT Scan. Computed tomography (CT) scanning is performed by taking high-resolution X-ray images using a multislice scanner. This advanced imaging can detect coronary artery disease, evaluate congenital heart disease, and may be used to evaluate a patient s heart prior to a complex catheter ablation procedure. Magnetic Resonance Imaging. Cardiac magnetic resonance imaging (MRI) is a painless means of evaluating the heart s structure and function. It can sometimes detect rare heart conditions (such as arrhythmogenic right ventricular dysplasia and cardiac sarcoidosis) and involves no radiation. MRI scans are sometimes obtained prior to complex catheter ablations. MRI of other parts of the body is also a useful diagnostic test for patients with various kinds of medical problems. In the past, MRI was not allowed in patients with implanted cardiac pacemakers and defibrillators. Thanks to the research efforts of several physicians and researchers, including those at The Johns Hopkins Hospital, MRI can now be safely performed in many patients with implanted cardiac devices. Electrophysiology Study. Some arrhythmias are difficult to diagnose and may require an electrophysiology (EP) study. An EP study is often used to evaluate patients who have fainted or have experienced an abnormal rapid heart rhythm. This test may be recommended for patients who have impaired heart function and intermittent extra heartbeats, even if they are not experiencing symptoms. In other circumstances, patients with an inherited cardiac condition may undergo an EP study as part of their risk assessment. In these cases, the EP study may identify patients who are at high risk of developing a serious arrhythmia indicating the need for preventive treatment. In an EP study, an electrophysiologist inserts several intravenous (IV) lines into large veins. The electrophysiologist then passes several electrical catheters through the IVs and guides them into the heart using X-ray imaging. This allows the electrophysiologist to examine the electrical activity inside your heart to determine if and why the rhythm is abnormal. Once that is known, your physician can prescribe the most effective treatment. 23